Aluminosilicate glasses for ion exchange

Abstract

Glass compositions that may be used to produce chemically strengthened glass sheets by ion exchange. The glass compositions are chosen to promote simultaneously high compressive stress and deep depth of layer or, alternatively, to reduce the time needed to ion exchange the glass to produce a predetermined compressive stress and depth of layer.

The invention claimed is: 
     
       1. An alkali aluminosilicate glass comprising:
 from about 16 mol % to about 20 mol % Al 2 O 3 , Fe 2 O 3 , and from about 15 mol % to about 20 mol % of at least one alkali metal oxide R 2 O selected from the group consisting of Li 2 O, Na 2 O, K 2 O, Rb 2 O, and Cs 2 O, wherein R 2 O includes 15 mol % to 20 mol % Na 2 O, 0 mol %>Al 2 O 3  (mol %) −Na 2 O (mol %)≥−4 mol %, and the alkali aluminosilicate glass is ion exchangeable. 
 
     
     
       2. The alkali aluminosilicate glass of  claim 1 , wherein the alkali aluminosilicate glass comprises: from about 55 mol % to about 70 mol % SiO 2 ; from about 16 mol % to about 20 mol % Al 2 O 3 ; Fe 2 O 3 ; from 0 mol % to about 10 mol % B 2 O 3 ; from 0 mol % to about 5 mol % Li 2 O; from 15 mol % to about 20 mol % Na 2 O; from 0 mol % to about 5 mol % K 2 O; from 0 mol % to about 10 mol % MgO; and from 0 mol % to about 10 mol % ZnO. 
     
     
       3. The alkali aluminosilicate glass of  claim 1 , wherein 15 mol %≤Li 2 O+Na 2 O+K 2 O≤20 mol %. 
     
     
       4. The alkali aluminosilicate glass of  claim 1 , further comprising at least one divalent metal oxide. 
     
     
       5. The alkali aluminosilicate glass of  claim 4 , wherein the at least one divalent metal oxide is at least one of MgO, CaO, BaO, SrO, and ZnO. 
     
     
       6. The alkali aluminosilicate glass of  claim 5 , wherein the alkali aluminosilicate glass contains 0 mol % B 2 O 3 . 
     
     
       7. The alkali aluminosilicate glass of  claim 1 , wherein the alkali aluminosilicate glass is free of divalent metal oxides. 
     
     
       8. The alkali aluminosilicate glass of  claim 1 , wherein the alkali aluminosilicate glass is ion exchanged and has a compressive layer extending from a surface of the alkali aluminosilicate glass into the alkali aluminosilicate glass to a depth of layer. 
     
     
       9. The alkali aluminosilicate glass of  claim 8 , wherein the compressive layer is under a compressive stress of at least 1 GPa. 
     
     
       10. The alkali aluminosilicate glass of  claim 9 , wherein the compressive layer is under a compressive stress of at least 1.1 GPa. 
     
     
       11. The alkali aluminosilicate glass of  claim 8 , wherein the alkali aluminosilicate glass has a nanohardness of at least 7 GPa. 
     
     
       12. The alkali aluminosilicate glass of  claim 1 , further comprising at least one fining agent. 
     
     
       13. The alkali aluminosilicate glass of  claim 12 , wherein the fining agent comprises at least one of SnO 2 , As 2 O 3 , and Sb 2 O 3 . 
     
     
       14. The alkali aluminosilicate glass of  claim 1 , wherein the alkali aluminosilicate glass is free of divalent metal oxides other than MgO and ZnO. 
     
     
       15. The alkali aluminosilicate glass of  claim 1 , wherein the alkali aluminosilicate glass has a liquidus viscosity in a range of at least about 20 kiloPoise to 64 kiloPoise. 
     
     
       16. The alkali aluminosilicate glass of  claim 1 , comprising about 1 mol % Fe 2 O 3 . 
     
     
       17. The alkali aluminosilicate glass of  claim 1 , wherein the Al 2 O 3  is present in tetrahedral configuration. 
     
     
       18. A touch-screen device or hand held electronic device comprising the alkali aluminosilicate glass of  claim 1 .